Like Podagritus, Williamsita species are boldly colored wasps, usually principally black with contrasting yellow or orange markings. They differ from Podagritus species in being extra sturdy with the bottom of the gaster not notably pedunculate. Different distinguishing options embrace the presence of distinct foveae (pits) towards the margins of the eyes (sometimes much less distinct in males), thirteen-segmented antennae in males, and a pygidial plate in each sexes that’s narrowed and concave in females, quadrate in males. Williamsita species additionally do not need the palps decreased as in Podagritus, as an alternative having the extra typical association of six segments within the maxillary palps and 4 segments within the labial palps (Bohart & Menke 1976).
Up to now, eleven species have been recognised within the genus Williamsita (Leclercq 2006). Most are present in Australia with a single species every identified from New Caledonia and Vanuatu. Leclercq (1950) recommended dividing the genus between two subgenera with all species besides the New Caledonian kind species W. novocaledonica forming a subgenus Androcrabro. Options supporting the latter taxon included the presence of ventral notches on a number of segments of the antennae in males. Nevertheless, Leclercq later recommended abandoning such a proper division, questioning its significance (Leclercq 2006). The Australian species of Williamsita are, nonetheless, distinct from the 2 insular species in being marked with a lot stronger punctation over the physique.
Most Williamsita species stay little seen and poorly identified. Nevertheless, breeding habits have been recorded for 2 Australian species, W. bivittata and W. tasmanica (Maynard & Fearn 2021; McCorquodale et al. 1989). Each these species nest in branching holes in rotting wooden, both commandeering burrows left by wood-boring bugs or excavating their very own. Prey consists of bigger flies akin to blow flies or soldier flies which had been carried again to the nest by the wasp operating with the fly carried under the physique. As much as six paralysed flies is likely to be positioned mendacity on their backs in a nest cell with an egg laid throughout the ‘throat’ (i.e. on the joint between head and thorax) of one of many flies. The cell would then be closed with a plug of woody frass. McCorquodale et al. (1989) recorded W. bivittata developing a number of such cells in a collection alongside a single tunnel, whereas Maynard & Fearn (2021) discovered W. tasmanica extra prone to place a single cell in a side-branch. As each observations had been restricted to a single location in a single season, although, one would possibly fairly query whether or not these symbolize true variations in species behaviour or had been decided by accessible situations. There is a restrict to how deep a Williamsita can burrow.
Bohart, R. M., & A. S. Menke. 1976. Sphecid Wasps of the World. College of California Press: Berkeley.
Leclercq, J. 1950. Sur les crabroniens orientaux et australiens rangés par R. E. Turner (1912–1915) dans le style Crabro (subgenus Solenius). Bulletin et Annales de la Société Entomologique de Belgique 86 (7–8): 191–198.
Leclercq, J. 2006. Hyménoptères crabroniens d’Australie du style Williamsita Pate, 1947 (Hymenoptera: Crabronidae). Notes Fauniques de Gembloux 59 (2): 115–119.
Maynard, D., & S. Fearn. 2021. Ecological and behavioural observations of a nesting aggregation of the endemic Tasmanian digger wasp Williamsita tasmanica (Smith, 1856) (Hymenoptera: Crabronidae: Crabroninae). Papers and Proceedings of the Royal Society of Tasmania 155 (1): 43–50.
McCorquodale, D. B., C. E. Thomson & V. Elder. 1989. Nest and prey of Williamsita bivittata (Turner) (Hymenoptera: Sphecidae: Crabroninae). Australian Entomological Journal 16 (1): 5–8.